Puzzled
by Juliettaah
Summary: There's always a story, but sometimes the killer is the only one to know it. Will Castle and Beckett be able to put the pieces of the puzzle together before it's too late?
1. Prologue

**So, finally a multi-chapter story. With a plot. Eeeeep.  
**

**As scared as I am, most of the story is already written down so I won't back down from this! Except if you want me to... I guess.  
**

**The story is set around the beginning of S5 and is not related to any episode.  
**

**Thousand of thanks to Kelli (KelliP if you want to -and you should- read her stories) for being an awesome beta.  
**

**Disclaimer: I feel like we all said it too much already.**

* * *

**Prologue**

Another boring meeting. _Again_. Another of these occurrences when he had to listen to everything they say he should do. When he _knew_ they're wrong. Because he knew better.

He was tired of this life.

It'd been so long before anything new, anything _distracting_ had come onto his path.

He had put a stop to his previous _career_. His debauched history.

Ha, that was an understatement.

He didn't see anything illegal in what he had done though. What truly mattered was the shot of adrealine who roared in him. Who drove him and made him better, greater.

Now it was gone. Inexisting. Just like himself. Now he was some kind of flunkey, only good to listen to the others. Only good to be censored.

He tried to look out for it. The nostalgia and the thirst of blood visited him on a regular basis. It was addictive. He had thought he could run away from it but it kept coming back, kept making him suffer.

Of course, he was confronted with blood and crime at his job but it wasn't enough. It wasn't the same because it wasn't really _him_.

He asked himself how he did it all this time, how he did not crave, why he didn't do anything to remedy to this need.

Because yes, he _needed_ it.

* * *

Maybe it was this urgency, the withdrawal who talked but when he saw her, everything shone with a new light.

She was _perfect_.

He looked down at the time. He was early. Good. Not that he cared anyway, not when _she_ was in front of him.

He admired the curves of her body. Oh yes, perfect was the right word.

Was she single? That would be unlikely... A flash of anger rushed through him. _How could she be anyone else's but his_? He soon cooled himself down. It could be all for the better, it could be more challenging. She could only resist him for so long.

Like a prowler, he followed her. At least she was alone at the moment.

He approached her.

Discreetly.

Dangerously.

She stopped in front of a bookstore to watch the shop window where the books of the latest fashionable writers were displayed. _Interesting_. If she was _attracted_ to murders, he could host her a private show. Open a whole new world to her.

* * *

All his senses were awake. He slipped behind her and, thanks to a gust of wind, he got a whif off her scent.

Delicious.

He couldn't put a word on what he just smelled but he was planning to discover it. And to feel it again. And again.

Lost in his contemplation and in his thoughts, he didn't notice she was fast walking away.

No.

No. He couldn't let her get out of his sight. He finally found the big occasion, his big return.

He carefully got out his cellphone and felt very grateful for new technologies. A camera at hand, no one able to see him and he would be able to _think_ of her anytime.

Give him courage if he swayed.

Help him until the end.

She wouldn't escape from him.

Satisfied with the few snapshots he managed to take without anyone noticing, he went hunting for the next stage, the hardest one.

To find who she was.

New York was a big city, he couldn't leave anything to the hazard. She might be here only because she was at a friend's last night, or maybe because she just spent a night of passion with a stranger – the idea made him shudder – and then he wouldn't ever find her again.

He couldn't do anything right away. Not in broad daylight, in the street, when he was too unfocused and still relieving from his discovery, when he was subject to do mistakes.

He had to get back to _work._

For her.

He would put a new plan into action. Infallible. He was counting on spending a long time on her company with no one to ever find her again.

He looked at her face more closely. Confidence and courage sprung from her. She was probably intouchable. But he liked a good challenge. She probably would put a fight. But he'd succeed. He wouldn't give her a chance.

He would have to be ingenious, subtle. Find her weaknesses. Break her defenses.

He'd find how to do it. He'd do it.

He could see in her eyes some glow of uncertainty, or maybe was it sadness.

He'd show her he was everything for her.

* * *

He saw her stop in front of a building and enter it. He looked up to see what it was. And he smiled. Maybe it was destiny who brought him to stumble upon her.

She might be hard to get but she would be easy to find. He couldn't have found someone better.

He had everything in his hands.

Everything was boiling inside of him.

Finally, a feeling of life he hadn't felt in so long.

It was time he went to his meeting. But he couldn't care less, he wasn't dreading it anymore. Oh no, not when he had something else on his mind and when he knew exactly _who_ was going to help him through it.

* * *

_I know, our favourite duo and team weren't there just yet. But don't you worry, the rest of the story is all about them._

_Thoughts?_


	2. Unknown

**Here you go, dear friends!  
**

**Thanks to everyone who followed and reviewed, it means a lot.  
**

**Before it starts, can I just say how much I love Lanie?**

* * *

**Chapter 1 : Unknown**

"What do you have for us, Lanie?"

"Hello to you too, Kate. And Castle," she added with an intent look towards the writer.

She was still amazed and amused to see them so synchronized they arrived at the same time to the crime scenes, even though they didn't come together.

Castle didn't answer at first, busy looking around him and taking in the setting of the outdoor subway station.

Faithful to himself, he acknowledged her with a sarky comment. "Tell me Dr Parish, is that you bothering the subway traffic so soon in the morning?"

Lanie shot him a bored look before asserting, sarcastically. "Of course, Castle, I don't have enough problems with the dead, so I decided to mess with the living now."

Castle got back to her with the same dry smile, but gulped, a glimmer of fear shining in his eyes. He'd rather have the wrath of Dr Parish remain to the dead, she was already intimidating enough.

"By the way, what do you know about the subway? Ever stepped foot in it?"

Castle made an attempt to look offended but didn't come up with a witty retort. He just mumbled, justifying himself. "I heard it on the radio this morning... in the cab," he finished lamely.

Kate snickered. Which made Castle even more sulky. He pursed up his lips and folded his arms. Even though most part of this conversation was teasing, he couldn't help but be concerned that Kate didn't approve of his way of life... Although he didn't have to keep his pouty attitude for long as Kate elbowed him and threw him a dazzling smile. He was reassured right away and smiled back at her.

He got lost in his emerald eyes for a few seconds...

Enough time for Lanie to notice and clear her throat.

"When you're finished making goo-goo eyes at each other maybe we can move on to our friend, here, or what's left of them anyway."

Kate turned red while a smug smile took residence on Castle's face.

From the corner of his eye, he saw her biting her lip and felt the need to kiss her. _Lanie wouldn't mind, after all she rooted for them all this time_...

His intention was ruined fast because in the blink of an eye, in a way only she was able to, Beckett got straight back into cop mode.

"What's left of them? What do you mean?"

"It's better if you come see for yourself." She looked between the two of them. "I hope you didn't eat too much this morning..."

* * *

"Oh, Jesus."

No matter what was in their stomach, a wave of nausea hit them. Even Lanie, who had already seen the scene, had to put her hand in front of her mouth for a moment. The sight offered to them was probably among the worst they ever had to face. They almost had to guess to see the remains of a corpse, only pieces of flesh spread out on the rails along with pools of blood. Some remnants were hanging from the wheels of the train, leaving no doubt as to the reason how the victim had been killed.

After quickly inspecting the scene, Beckett and Castle stepped back and took a deep breath into the fresh air to recollect themselves. Beckett broke the silence first.

"Lanie, what are we doing here? There are dozen of people committing suicide under a train every month, what does it have to do with us?"

"Well, it's possible our suicidal friend here has had help, if you know what I mean."

Castle chimed in, a disgusted look still present on his face. "How do you know? His guts told you that?"

"Very funny, Castle. Actually it was the driver, who 'witnessed' the scene that told us. He distinctly saw someone push our vic under the train when it arrived." She almost added something but dithered. Beckett immediately saw there was something her friend was not telling them. She was about to interrogate her when an uniform came in.

"The driver couldn't make any identification nor drawing of the suspect. It seems he was wearing a hood, sun glasses and dark clothes. The only thing we're sure of is that it was a man. Maybe you'll know more when you'll interrogate him, when he... recovers."

"Other potential witnesses?"

"Not a soul. Most of the workers weren't up just yet and this station seems deserted even in rush hour."

"Cameras?" Beckett knew her question was a long shot but without witness, without corpse and without suspect, the investigation looked to be laborious, to say the least.

The uniform looked at them with sorry eyes and went back to the forensic team since they probably needed him to recover the various... pieces of the body.

Castle turned back to the detective and the medical examiner, "Are we sure it really is a murder? I mean, for all we know, the driver had hallucinations or wasn't awake just yet."

Beckett answered him, "We'll see..." and saw her friend scowled. She remember her odd behavior a few minutes earlier. "Anything else, Lanie?"

She looked at them, saddened. "The driver said something else. About the victim. It was a girl. A young woman, barely an adult."

Castle and Beckett turned pale.

She added, "I can't tell for sure at the moment but it's highly possible..."

Castle looked swamped.

Beckett turned to Castle. "Call Alexis."

"No, I'm... I'm okay. It's not her, I know."

"You know you want to. You need to. Go, I'll wait for you in the car."

It was one of these moments he felt grateful to have her in his life. He wondered if he deserved this. Her.

She observed him, worried, while he was moving away, phone close to his ear. _It was going to be a difficult case_.

* * *

_Thoughts? :)_


	3. Trust

**Thanks to everyone who read, follow and review this story.  
**

**Special thanks to KelliP for her great ability of beta-ing even when she's dying in bed. :)  
**

**By the way, how awesome was last night's ep?!  
**

* * *

**Chapter 2 : Trust**

Back at the precinct, Castle was surprised not to spot their two companions.

"Where are Rysposito?"

Beckett, grinning in spite of herself, shot him a look. "They're looking for potential witnesses."

Castle raised his eyebrows, but before he could even open his mouth, Beckett stated, "I know, I know, there is little chance they'll come back with anything. But at this point, it's our only hope if we want to start the case."

"What about the driver?"

"They're bringing him in, I'll question him soon, or try to, since apparently he is still in shock."

Beckett sighed and ran a hand through her hair.

Castle tried to lighten the mood. "You know what they say, all the subway-drivers have to go through their suicide baptism."

He made a face, thinking about what he just said. "Mh. Nice choice of words."

Beckett cast him a weak smile, even though she couldn't hide her amusement and tenderness towards the writer... and his morbid humor.

Castle wasn't satisfied with it. He looked to the right and to the left. Good, they were isolated. He jumped on the opportunity to break the no-PDA-rule. He circled her shoulders with his arm and pulled her to him.

He wasn't sure what to say. He wished he could make her laugh but they barely had any element that could even help him support an eccentric theory. Since he had learnt that a hug often was the best soothing and comforting device for Kate, despite what she might say, he hoped his warmth would do the trick, lull her.

Indeed she didn't push him away, instead rushed into his arms.

He put his hand on her cheek and lifted her head so their looks could collide.

"Hey. It's going to be okay. We're going to get to the bottom of this."

Well, maybe he couldn't stay silent after all.

He was aware of the burden this case represented for the detective and how much it weighed on her shoulders. She had been back on the job only for a couple weeks and Gates was still on the look out. Castle doubted Gates would rank her down but Kate still felt like she was put to trial, like she needed to prove herself... _When did she not_? he thought.

He leaned down to drop a sweet kiss on her lips when they heard a door open bruskly. "Beckett, in my office!"

They untangled themselves at an unlikely speed, trying to look like anything but children caught red-handed.

They adopted an innocent position and looked up to come face to face with Gates, sending a suspiciouslook at them. If there was only one person to hide their relationship from, it was her. They were thinking about finally sharing the news with their friends but they had to be discreet. Even Castle who had doubts was now afraid of what Gates' reaction might be. Despite what he told Kate he didn't want to stop their partnership. Sure, their relationship was better than anything he could have dreamt of, but working with her was exhilarating and inspiring. What would he do with his life if he had to stop? Probably feel useless, mope around and be constantly worried that something happened to her. Because he wasn't there to protect her. Yes, she was the cop but there was no reason he couldn't be there for her too.

"Coming back," she whispered at his ear, as cautiously as she could. When she untied herself from him he immediately felt the loss of her love.

He also had the feeling this case was going to be perilous, and he couldn't wait before they would go back home, back to the passion and the warmness of Kate.

* * *

"So detective, how is this case going?"

Kate made a face. Which Gates, raising her eyebrows, didn't miss.

"Well... we're waiting for the results from the lab. No ID for now and the only witness available is in shock and not really willing to give us informations."

Gates sighed. "Very well. Do your best Beckett. The sooner this case is closed, the better."

Kate couldn't stop herself from being ironic. "Are there times when it's not?"

Gates ignored her but answered frankly. "You know the number of people taking the subway to go to work? The last thing we need is panic because a psychopath throws people under a train!"

"Sir, excuse me but nothing indicates he'll kill again."

"And on what are you basing this, detective?"

Kate had to admit the profile of the killer was at zero point and that no hypothesis was to be put aside.

Gates interpreted correctly her silence. "Exactly detective. For now, not a word to the journalists. Our case looks like a suicide, let them believe that. They will leave us in peace. Now, do your job and solve this case soon."

* * *

As soon as he saw Beckett leave, Castle rushed up to her.

"What did she want?"

"Oh, the usual. Check that I do my job, tell me not to disclose anything related to the case," she groaned, rolling her eyes.

Rick held her a coffee cup he got ready for her, since it was the best way to give the detective some courage and help her stay awake in prevision of the long hours ahead of them.

"So, where do we start?"

"Not with the witnesses in any case." Beckett and Castle lifted their head up at the sound of Esposito's voice, coming in with Ryan.

The latter confirmed. "Nobody heard nor saw anything and we didn't find any camera around."

"It looks like the countryside right in New York," grumbled Esposito.

Beckett assimilated the -thin- information they provided her and tried all the same to draw some conclusions... so they could at least start the case.

"Well, then we can assume the killer chose this station knowingly. He didn't want to be seen and wanted to be sure he could get away."

"It's risky. How could he be sure nobody was going to be there?" Castle observed.

It was Esposito's turn to participate, "Maybe he was ready to run the risk."

Castle had an embarrassed expression. "It doesn't bother you the way he killed her? It didn't seem very personal..."

"You think it was random?"

Ryan went on. "Then how come the vic is a young woman who seems to be not to be missing for anyone?"

An uneasy feeling flied into the atmosphere.

Beckett tried not to let herself get to overwhelmed. She could see how it was affecting Castle. Especially since he couldn't see her as much as he'd like to, he was constantly worried about her and her well-being. This case was _not_ what they needed so soon after she left.

As much as she'd like to tell him to let them handle the case and go see Alexis, she couldn't stop the little egoistical voice who wanted to keep Castle by her side. A case with a teenager was as difficult as it was with a child. The presence alone of Castle comforted her, gave her energy.

"Maybe our suspect wasn't in full command of his capacities, drunk, drugged... Maybe the girl was standing in his way, maybe she did something he didn't like..." Beckett's mind was in overdrive. It was possible it was the key of the mystery. But this would mean they had no way of finding the killer.

Every one was thinking about this hypothesis and seemed satisfied. Except Castle. Beckett saw him brewding over it and questionned him about what was bothering him.

"It's just... Um. Everything would fall so well into place. A abandoned station, an elusive killer and a girl no one is looking for? You know it as well as I do, Kate. Such coincidences don't exist."

Before he could react, he called her Kate. Her name flew on his tongue so tenderly the boys couldn't not have noticed it. It was still unusual at the precinct and the surprised smirk displayed on their face they were trying to hide confirmed it hadn't escaped them either. However just as she didn't have the heart to scowl at him, they didn't comment.

Esposito went on right away. "Castle isn't wrong." He paused and tentatively added, "a contract killer?"

Three heads turned to him, unconvinced. Ryan shook his head. "Parents who'd want to get rid of their child? A desabused lover? Nah, I don't believe it. Plus, there are plenty of other ways they could have done it... more carefully," he finished, serious.

"Unfortunately, we can't leave out this theory. But without any ID we won't go far," Beckett concluded.

At this exact time, Beckett's phone rang. They looked at each other, hopeful.

"Beckett. (…) Okay, we're on our way."

In the blink of an eye, she had her coat on her arm, the phone hung up and with a tilt of the head towards Castle, she said, "It was Lanie. She has something for us."

Esposito muttered something like "Let's hope it's good news," as the duo went in the direction of the morgue, and he went back to his desk.

* * *

_I know this chapter was pretty heavy on the case but I hope you liked it anyway._

_Don't worry though it all leads to Caskett goodness. ;)_


	4. Odd

**Thanks to everyone who gave a chance to this story.**

* * *

**Chapter 3 : Odd**

Castle and Beckett arrived at the morgue, hand in hand, in a rare moment of intimacy. They usually managed to obey the strict rules about PDA they - _Beckett_ - had established in the precinct and in the work field, as hard as it could be - and despite Castle who had tried to break them in some very creative ways. But it seems it wasn't on today. It was different. It was probable that this case left them with little time for themselves, alone together, unclouded minds, and they wanted to enjoy each other's company, as much as they could.

This attitude was so natural for them that their hands were still entwined even though they had crossed the doors of the morgue where Lanie was standing. To whom this detail didn't fail to escape.

"I see you two lovebirds are twice as careful as to hide your relationship," she mocked them.

Having forgotten their proximity, they were surprised by the remark of the ME, and even more that they had been so oblivious to their closeness. Their hands quickly separated, not without a pang.

If they kept her relationship secret - and enjoyed this intimacy so they could play secret lovers at work, which _extremely_ turned them on - the threat Gates represented was serious and they'd rather avoid it for now. However it wasn't long before Lanie caught them. Not in the act but close enough. She saw right through their little game and above all through the blazing smile of her best friend. It was hard to miss the glowing happiness of the young woman during the last months.

"So you have something for us?"

Heading towards the corpse, Lanie went back to being serious.

"You could say that. Can't say the killer made it easy for me," she said, gesturing towards the corpse's scattered pieces, "but I can already confirm it was a young woman. I might not have been able to tell if I hadn't known it first but it's coherent."

They couldn't say the confirmation made them content, but at least that was something.

"At least, we can focus on some relevant research for missing persons," Beckett said, not really optimistic.

"Not that I want to tell you how to do your job, Dr Parish, but can't the teeth give you more details or certainties?"

Lanie glared at him and said sarcastically, "You did your homework Castle?"

"Hey, I still use our cases for research!"

"Mh mh. Well, they usually can. Except they're not here. It's possible the train crushed them all. But it's more likely they were already in bad condition and couldn't remain after the impact."

"So, not a girl from a well-off family..."

Lanie gave her a nod. "I'd even say she could have been living in the street, or something of the kind."

Beckett turned to Castle, who was now absorbed in the mess laid out in front of his eyes. The sight still wasn't pleasant but it was cleaner and without the smell, he could finally and truly examined the remains of the woman.

"What is this?" he asked, indicating some strange red marks, on some parts of the pieces.

Lanie looked at Castle, amused and impressed.

"It's the second thing I wanted to talk to you about. I looked closer and I found these marks several times, including on what is left of the bones."

Castle and Beckett looked at her, perplexed, in a hurry to know what would come next.

"I don't think the impact of the train killed her. I think she was killed before. Beaten to death."

It was too much for Castle. He rushed to the closer bin and emptied everything that could be found in his stomach.

* * *

Before they got back upstairs, Beckett took advantage of the discretion of one the morgue's corridors to hold a private conversation with Castle.

"Castle, go home. You're taking this case too much to heart, it won't do you any good to work on it, _if_ we even solve it."

"Kate, I'm okay. I promise. I'm not saying it's pleasant, I'm not saying I won't have nightmares at night but it is not different from any other case. Look at you, _you_ don't have a choice."

"It's my job! I don't have a daughter and you have the choice. You should take advantage of it."

"And leave you alone? This case affects you as much as it affects me. There's no way I'm leaving you, I want to be there for you."

Kate was moved by his words, and in this moment more than any other one, she knew why her love for him was so strong. But she wanted to watch over him, and this case wouldn't do him any good.

"Rick..."

She didn't have the time to finish her sentence before his lips brushed over hers. He put his hands on both sides of her face, hoping he could convey all his love and all the reasons that made it useless for her to insist, hoping she'd understand he's not giving up.

She returned his kiss with as much softness and passion, but managed to keep it under control. After a few minutes, their lips came apart and they both exhibited a loving smile. Kate took his hand and brought him with her towards the exist, whispering a firm "come on," like she could have had the time to turn into cop mode. Castle was still grinning foolishly, his thoughts wrapped around Kate... and the fact that he was glad he had always some chewing-gum on him for the right occasions.

* * *

_Feel free to tell what you think!_


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